Araucaria excelsa (Christmas tree)
Araucaria excelsa (Araucariaceae) is a beautiful,evergreen, conifertree of pyramidal shape which reaches up to 65-70 m tall in its original habitat. It is native to Norfolk Island (a sub-tropical Island in Pacific Ocean). It is also known as Christmas tree, Norfolk Island Pine,Andes pine and Australian Pine etc. It is the synonym of Araucaria heterophylla. The tree has straight vertical trunk that is 1.25-1.75 m in diameter. The branches are heavy, horizontal and spreading throughout without any support. The leaves or needles are crowded together on branches in spiral shape. The mature needles are ovate and scale-like. The male cone is 5 cm long, oblong in shape while female cone is erect, sub-globose in shape, 10-12 cm long and 12-15 cm in diameter. The seeds are oblong in shape, winged and up to 3 cm long& 1.2 cm wide.
Araucaria excelsa can be grown as ornamental plant that reaches up to 1-2 meters in height when kept indoor. It grows slowly in indoors approximately less than 15 cm a year which makes it an attractive plant at homes, living rooms and entrance halls in containers. It is the only specie of Araucaria which can be used as indoor Christmas tree. It can also be planted outdoors separately in gardens, streets and avenues. The tolerant nature of plant from salt and wind makes it an ideal plant for coastal areas in tropical and sub-tropical regions.
How to propagate
Araucaria excelsa can be propagated through seeds or cuttings. The cuttings taken from dynamic material will grow upright but the cuttings taken from horizontal branches will maintain horizontal growth instead of normal upright growth. The rooting take place within 2 to 3 months. The plant should be planted in large enough container for it rooting. However, it will take several years to reach the size of purchased plant.
How to take care
- Araucaria excelsagrows well in medium light.
- It prefers well drained soil however, it can grow on acidic and salty soil.
- The ideal temperature for plant growth is 7-24˚C.
- It prefers relative medium humidity therefore, occasionally mist spraying is required.
- The plant will show loss of needles if the atmosphere is too dry or exposed to sun.
- If the plant is kept in indoor in a container, then it required enough space to spread its roots.
- Do not allow the water to stand in pots because it do not need much water.
- It do not needs pruning at all but dead branches should be removed.
- It is tolerant to the frost but extremely low temperature cause damage to pot plants.
- It required liquid fertilizer after every two weeks for rapid growth.
- The most common disease of this plant is “Stem rot” which turns the stem into brown coloration that leads to the death of plant.
- Mealybugs are the most common pests of Araucaria that cause white areas on leaves and stems but can be removed by spraying with appropriate pesticide.
Uses of Araucaria excelsa
- The wood is soft, high quality and good for turning. At one time it was used heavily for construction purposes.
- It is grown as an ornamental houseplant in areaswhere winters are too cold and used as a Christmas tree.
- The stem releases resin and gum which showed antiulcerogenic and antibacterial properties.
- Its leaves used as an effective, cheap and environmental friendly biosorbent that removes chromium (Cr) and lead (Pb) from nature.
- It is one of the 50 plants listed by NASA that have air purifying property and reported to absorbed formaldehyde.
- It has gained the Royal Horticulture Society Award of Garden Merit.